AB Control Logix Gateway

[Ajwy]

Hi all,

I’m seeing a Workstation at node10 when I open the Routing Table, these are off the ENET card and have node numbers instead of IP addressed. I can right click and edit the node number etc but if I try to add a workstation I can only choose IP address. This is a relatively old system from approximately 2005.

I’m just wondering what the Workstation is. They aren’t DH+ nodes.

The control Logix gateway is a bridge between approximately 12 SLC505s and 3 SLC504s so just allowing MSG instructions between different networks. The DH+ PLCs don’t route out to the Ethernet/IP network. But the Ethernet PLCs use MultiHop msg instructions to msg the DH+ PLCs

Thanks for any help

 

[Lem]

Wouldn't that actually be the PC you are currently connected to it from?

 

[Ajwy]

No, this is a Routing Table in the DH+RIO card. This shows the Items that have been added for connections. This isn't my laptop. I'm wondering if it is an old removed SCADA PC that would have had dual drivers for IP and DH+ connections that has since been removed.

 

[Ken Roach]

I think you're probably right about that object being in the routing table because it was an RSLinx workstation on Ethernet.

It could have been used as the target object for unsolicited messages from controllers on DH+.

Or, it could have been put in by mistake or by default by the old RSLinx routing table tool. The Link ID's look like they are defaults: I think that when you put in network devices on Ethernet they got default Link ID's starting at 16 and decreasing on each hop.

Separately, Link 2 is default for a DH+ channel, which is why the DHRIO Channel A is set for Link 2.


This stuff is... tricky.

 

[Ken Roach]

the Ethernet PLCs use MultiHop msg instructions to msg the DH+ PLCs

I think when you examine the MSG instructions in those SLC-5/05's, you will see that they are set up for Remote type (as opposed to Local).

Remote messages include a Destination Link ID and Destination Station Number, as well as an actual target Address.

These messages should have the target address as the 1756-ENET's IP address. The -ENET then receives the message and examines it. The 1756-ENET's internal monologue goes something like:

"It's set for Remote, so I should check my routing table"

"The routing table says Link ID 2 is Channel A of the 1756-DHRIO. I will send this message to the DHRIO over a CIP path, which is just one backplane hop, to process"

The 1756-DHRIO then receives that message and processes it on Link 2 (channel A) to the destination DH+ address, an SLC-5/04 controller.

When it gets a response, it sends that response using CIP protocol back to the 1756-ENET, which in turn sends it back to the originating SLC-5/05 controller with either a data read payload, or a data write acknowledgement, or an error code.

 

[Ajwy]

Hi Ken, Thanks for reply. What's confusing is I can edit the Workstations node and Link, but if I add a new Workstation it only give me the option of link and an IP address not Node address.
I only have MultiHop Local MSGs in the SLC5/05s targeting the SLC5/04s. and no MSGs from 5/04s targeting the 505/s except 1 PLC has 1 MSG which is indeed setup as REMOTE but this is in error and the error msg is no IP address.
Because the system was put in in around 2005 I'm assuming it's never worked and legacy.

 

[Ajwy]

Update, Just gone onsite and checked the MSG. The Remote MSG does in fact work, and is bringing back information from an SLC505. So I'm guessing it is being routed via the unknown Workstation...

 

[Ajwy]

The Workstation is a SCADA Node at HEX A = Node 10. So thanks very much for help Ken.

 

[Ajwy]

Update, After talking to Rockwell Tech Support, RSLinx has corrupted the original Routing table and changed the Icon to a WorkStation instead of a PLC and the Node is the first Octet of the IP address, but that's all it shows. The Link 16 is OK though. So you actually have to recreate a new Routing Table. These backups that were done using RSLinx xxx in 2002 - 2005 will be corrupted when using newer versions. If you have backup Routing tables see if you can open and how they look, do they contain IP address or Nodes ?